For example, a seat pad to be used for a vehicle seat typically includes a back pad that supports the back of an occupant and a cushion pad that supports the buttock of the occupant, and is molded using an expanded resin foam such as a flexible polyurethane foam or a semirigid polyurethane foam produced by expansion of an expandable resin material.
Regarding such seat pad, a technique in which grooves are formed in a seat surface of the cushion pad and a front surface of the back pad and a thin foam layer is stacked on the grooves and tunnel-like ventilation portions are thereby formed by the foam layer and the grooves to ensure ventilation and thus enables, e.g., temperature and humidity conditioning of the seat pad is known.
However, because voids are formed in the seat pad by the ventilation portions each formed in a tunnel-like shape, sitting on a seat using such seat pad including ventilation portions results in collapse of the vicinity of the ventilation portions and occlusion of the ventilation portions and thus results in depression of a part of a seat surface of a cushion portion of the seat and/or a front surface of a back portion of the seat. Therefore, failure to provide good sitting comfortability is conceivable.
As a countermeasure for such problem, Patent Literature 1 proposes a seat pad formed by integral expansion molding of an expandable resin material with a ventilation member included therein, the ventilation member having a function that lets air through to/from an outside and including an expanded resin foam subjected to film removal treatment.
In the seat pad according to Patent Literature 1, the ventilation member having a function that lets air through to/from the outside includes an expanded resin foam subjected to film removal treatment, enabling provision of good sitting comfortability with, e.g., temperature and humidity of the seat pad conditioned.
For integral expansion molding of a seat pad using an expandable resin material with such ventilation member included therein, first, a ventilation member is introduced and disposed in a mold and an expandable resin material is injected into the mold with the liquid disposed. Subsequently, the mold is heated to expand the expandable resin material, whereby a seat pad is molded integrally with the ventilation member included.